[Horst Weber]

Rod, Jim & Laurent

Me as a German native would explain it as follow:

An operational fighting-unit(Jäger, Bomber, Schlachtflieger) is flying an operational mission. This is called Feindflug, Feindeinsatz.

While flying this mission, they have contact with enemy a/c and losses due to this enemy a/c, the losses are described as "mit Feindberührung".

All losses like mechanical failures without an appearance of the enemy during a "Feindflug" are described as "ohne Feindberührung"

A good question is, if anti-aircraft fire, which caused a loss during a Feindflug, would have been described as "mit Feindberührung", too.
On my opinion, I would rather say, that "mit Feindberührung" was a loss to any enemy action while on a Feindflug.

Best regards !

Horst Weber